Add a helper function for inverted digitalRead

Author: ademuri

examples/debounce/debounce.ino

@@ -19,6 +19,9 @@ void setup() {
   // Typical usage: with a normal digital input
   button = new DebounceFilter(filter_functions::ForDigitalRead<kButtonPin>());
 
+  // For an inverted input, e.g. when using a button with a pullup resistor
+  button = new DebounceFilter(filter_functions::ForInvertedDigitalRead<kButtonPin>());
+
   // Advanced usage: custom input function
   button = new DebounceFilter(readButtonPin);
 

src/filter.h

@@ -181,6 +181,11 @@ static bool (*ForDigitalRead())() {
   return []() { return (bool)digitalRead(pin); };
 }
 
+template <uint32_t pin>
+static bool (*ForInvertedDigitalRead())() {
+  return []() { return (bool)!digitalRead(pin); };
+}
+
 template <uint32_t pin>
 static uint32_t (*ForAnalogRead())() {
   return []() { return (uint32_t)analogRead(pin); };